1. Field of the Invention
The present invention pertains to a hydrodynamic clutch device having a pump impeller inside a housing and a turbine impeller including a turbine shell connected non-rotatably to a turbine hub. A clutch device of this type is known in the form of, for example, a hydrodynamic clutch or a hydrodynamic torque converter and can be used in the drive train of a motor vehicle.
2. Description of the Related Art
Hydrodynamic clutch devices usually have a pump impeller, mounted in a housing, and a turbine impeller with a turbine shell, to which a turbine hub is connected nonrotatably. If the hydrodynamic clutch device is a hydrodynamic torque converter, a stator is also provided.
Hydrodynamic torque converters convert and transmit the torque produced by a machine such as an internal combustion engine. The pump impeller, the turbine impeller, and the stator are usually designed as curved shell components, and each wheel has a number of vanes. The individual wheels of the hydrodynamic torque converter run in the closed housing, which is filled with a working fluid.
In the normal case, the pump impeller is driven by the flywheel of the internal combustion engine via the housing at the rpm""s determined by the engine. During startup phase, only the pump impeller turns at first; the turbine impeller and, if present, the stator, are stationary. The working fluid flows from the pump impeller to the turbine impeller and transfers its energy to it. The turbine impeller is connected nonrotatably via the turbine hub to a shaft, which, in a motor vehicle, for example, is a take-off shaft or a transmission input shaft. As soon as the torque generated via the pump impeller on the turbine impeller is greater than the resistance torque of the shaft, the turbine impeller and thus also the shaft begin to turn.
In addition, hydrodynamic torque converters also usually have a bridging clutch, which is also installed inside the converter housing. Like a friction clutch, a bridging clutch of this type has the task of producing a slip-free connection, insofar as possible, between the converter housing and the shaft, such as the transmission input shaft. Individual components of the bridging clutch are usually also connected to the hub of the turbine.
Hydrodynamic torque converters of the general type described above are already known and are used especially in the automotive industry. An example is described in DE 198 38 445. In an exemplary embodiment presented in this document, a hydrodynamic torque converter is disclosed which has a pump impeller, a turbine impeller, and a stator inside a housing. The turbine impeller has a turbine shell and a connecting element, which are connected to each other. By way of the connecting element, the turbine shell is connected to one-part turbine hub, which is connected nonrotatably to the shaft.
In the case of a hydrodynamic clutch device, the turbine hub is called upon to perform several different functions. For example, it serves, first, as a connecting site for the turbine shell. If, in addition, a bridging clutch is provided, this clutch usually has a clutch piston, as will be described in further detail below. This clutch piston must be guided and driven. For this purpose, the piston has in the past been attached to and/or guided by the turbine hub. In addition, the stroke which the clutch piston can execute must be limited, and this has also been one of the functions of the turbine hub. Finally, the turbine hub also has the job of supporting various bearings such as axial bearings, roller bearings, plain bearings, etc.
When the hydrodynamic torque converter is equipped with a bridging clutch, this clutch usually includes a clutch piston. The radially outer area of this clutch piston, for example, can be provided with friction facings, which can, as a function of a pressure difference between the interior space of the converter and a chamber formed between the converter housing and the clutch piston, be pressed against an opposing friction surface of the converter housing. In its radially inner area, the clutch piston is usually sealed off against the turbine hub by the intermediate installation of a sealing element but still retains its freedom to rotate. The sealing element can be designed as a suitable sealing ring, which is held in a sealing groove made in the turbine hub. The turbine hub thus also has the function of making available an appropriate sealing ring groove.
Because of all these various functions which the turbine hub must fulfill, and because of the fact that heavy loads act on the turbine hub during the operation of the hydrodynamic torque converter, turbine hubs have been produced in the past as one-part components, which must be subjected to additional processing steps after their production. Thus, for example, it has been conventional in the past to produce turbine hubs as sintered metal parts or forgings, which are then machined in various ways. These metal-removing machining processes create appropriate contact surfaces and guide surfaces for the seating of the clutch piston, for the seating of sealing rings, for the connection of the turbine shell, etc., on the hub. In addition, the sealing ring groove described above must also be cut into the turbine hub, which can be done by means of, for example, a lathe-turning process.
These metal-removing machining processes in particular are very expensive and therefore disadvantageous. First, machining is time-consuming, because various work steps and processes are required to bring the turbine hub into it final desired shape after its rough shape has been produced. The production of a turbine hub is therefore also complicated structurally, because the sealing ring groove in particular must be produced in a highly precise manner. Finally, the metal-removing machining of parts suffers from the disadvantage that large amounts of waste material are generated, which must be stored separately and recycled. All in all, the production of turbine hubs as it has been done in the past is highly cost-intensive.
The object of the present invention is to improve a hydrodynamic clutch device of the general type cited above so that it can be produced easily in terms of construction and also at low cost.
According to the invention, a hydrodynamic clutch device, especially a hydrodynamic torque converter, is provided which has a pump impeller; a turbine impeller, which has a turbine shell and a turbine hub nonrotatably connected to it; and possibly a stator, all installed inside a housing. The turbine hub consists of several parts and the turbine shell is designed and mounted on the turbine hub so that it takes over some of the functions of the turbine hub.
As a result of the hydrodynamic clutch device according to the invention, it is possible to avoid the disadvantages of the state of the art described above. The hydrodynamic clutch device is not limited to specific design embodiments. For example, it is conceivable that the hydrodynamic clutch device could be designed either as a hydrodynamic clutch or as a hydrodynamic torque converter. To make it easier to understand the invention, it is described below on the basis of a hydrodynamic torque converter in particular, although the invention is not to be considered limited to this concrete embodiment.
The first basic idea of the invention is that the turbine hub is no longer designed as a single part but rather as a unit consisting of several parts. As a result, the individual components of the turbine hub can be easily produced first by suitable production methods. The individual parts of the turbine hub thus produced are then assembled to obtain the completed turbine hub. By providing the individual parts with the appropriate contouring and by assembling these parts appropriately to form the complete turbine hub, it is possible to eliminate the previously required metal-removing steps such as the production of the contact surfaces, the introduction of the sealing ring groove, etc.
At least some of these individual parts of the turbine hub can be made out of sheet metal.
Sheet-metal parts can be produced easily in terms of construction and thus at low cost, even when their contours are relatively complex. For example, the sheet-metal parts can be produced by methods such as rolling, upsetting, drawing, deep-drawing, pressing, and the like. The choice of a suitable process depends on the contour of the sheet-metal part to be made and on the selected material.
When the individual elements are designed in the form of sheet-metal parts, furthermore, it is possible to produce cavities in them, which leads to an advantageous reduction in the installation space and/or weight of the hydrodynamic clutch device. It is also possible to form grooves, such as oil feed grooves, snap connections, etc., in the sheet-metal parts. These structures can be produced much more easily in sheet metal than in the conventional solid turbine hubs and thus at lower cost.
By shaping the sheet-metal parts in appropriate ways, certain areas can also be produced which can function as xe2x80x9cdisk springsxe2x80x9d in the area of the axial bearings. As a result, axial play and/or bearing lift-off can be reduced, possibly even to zero in the most favorable case.
Another basic idea of the present invention is designing the turbine shell of the turbine impeller and mounting it on the turbine hub in such a way that it takes over certain functions of the turbine hub. As a result, the construction work involved in making the turbine hub and thus also in producing the hydrodynamic clutch device overall can be reduced even further.
Some of the primary functions which the turbine hub unit must perform were mentioned in the introduction to the specification. Some of these functions can now be taken over by the turbine shell, which reduces the amount of construction work required to produce the turbine hub. Examples of this are explained in greater detail in the further course of the specification.
As a result of the design of the hydrodynamic clutch device according to the invention, a simple structural solution is therefore created, according to which the turbine shell is integrated into the functions of a multi-part turbine hub. The components of the turbine hub can be made very easily and with little machining. In particular, the various required surfaces and stops can be easily produced by suitable shaping processes, as a result of which little or no metal-cutting is required. In addition, different bearing functions can be easily integrated into the individual components of the turbine hub or into the turbine shell. As a result of the multi-part design of the turbine hub and the integration of the turbine shell into the functions of the turbine hub, the required area which the ring-shaped surface of the turbine hub must have can be reduced, which also leads to a reduction in the amount of space required for the installation of the overall hydrodynamic clutch device.
It is advantageous for the hydrodynamic clutch device to have a bridging clutch, which has a clutch piston. As has already been described above, a bridging clutch of this type is advantageous when the hydrodynamic clutch device is designed as a hydrodynamic torque converter. The invention is not limited to specific types of bridging clutches. Thus, for example, it is conceivable that the bridging clutch could be designed in such a way that the clutch piston carries a friction facing and that this facing comes into direct contact with the adjacent converter housing. It is also conceivable, however, that the bridging clutch could be designed so that a disk is located axially between the cover of the converter housing facing the engine and a clutch piston, this disk being provided to accept friction facings and connected nonrotatably to the turbine impeller.
To be able to compensate for the vibrations which occur during the operation of the hydrodynamic clutch device, it is also possible to provide a torsional vibration damper.
It is advantageous for at least certain areas of the turbine shell to be designed as a guide element for the clutch piston.
It is conceivable, for example, that the turbine shell could form a radial guide surface for the clutch piston and that the clutch piston could be guided and/or supported in its radially inward area against a radially inner area of the turbine shell.
xe2x80x9cRadially innerxe2x80x9d and, later on in the specification, xe2x80x9cradially outerxe2x80x9d are to be understood as based on the rotational axis of the hydrodynamic clutch device.
The clutch piston does not necessarily have to be permanently connected to the turbine shell. For example, it is conceivable that the clutch piston could be supported only against the radial guide surface formed by the turbine shell. This facilitates assembly.
It is advantageous for the turbine shell to be shaped in such a way that it has an axial limiting surface for a sealing ring groove. In the past, the turbine hub has been the sole component responsible for providing the sealing ring groove; that is, the sealing ring groove had to be machined into the turbine hub on a lathe. Now, a part of the turbine shell can be integrated into this function of the turbine hub, that is, the function of providing the sealing ring groove, in that a certain part of the turbine shell represents an axial boundary surface for the sealing ring groove. In this way, the sealing ring groove is formed when the individual parts of the turbine hub are assembled with the turbine shell. This eliminates the need to remove metal from the turbine hub in a machining process.
For example, it is conceivable for the turbine shell to be mounted a defined distance away from the individual components of the turbine hub which form the other boundary surfaces of the sealing ring groove and for the complete sealing ring groove to be created only after assembly, where each individual component represents in and of itself only a part of the complete sealing ring groove.
It is advantageous for the axial boundary surface formed by the turbine shell for the sealing ring groove to be formed by a radially inner end of the turbine shell. In this way, no special constructive measures are required to form the sealing ring groove.
In a further elaboration, the turbine shell can have a radially inner contact surface for the insertion of an additional component. Through the appropriate design of the individual components of the turbine hub and of the turbine shell, receiving spaces can be formed upon assembly of the parts, into which the other components can be inserted. For example, these additional components can be pressed into the space thus formed. This facilitates the assembly of the hydrodynamic clutch device.
It is advantageous for the torsional vibration damper to be connected to the turbine shell and/or to the turbine hub and/or to the clutch piston.
As already mentioned, as a result of the hydrodynamic clutch device according to the invention with the multi-part design of the turbine hub and the integration of turbine hub functions to the turbine shell, it is possible for a receiving space serving as a sealing ring groove for the acceptance of the sealing ring to be formed between the turbine hub and the turbine shell.
In addition, the turbine hub, or one or more individual components of the turbine hub, can be designed as radial and/or axial boundaries of the sealing ring groove. An additional axial boundary for the sealing ring groove can be provided by the turbine shell. In this way, the cutting of a sealing ring groove, such as by a suitable turning process, becomes superfluous. Individual areas of the individual elements of the turbine hub or turbine shell, such as edges and/or surface areas, possibly flattened surface areas, serve as components of the sealing ring groove. After assembly of the individual components, these individual areas work together to form in their totality the sealing ring groove, into which then a corresponding sealing ring can be inserted so as to produce, for example, the seal described above with respect to the bridging clutch. The individual parts of the sealing ring groove in the various components can be produced easily.
It is advantageous for the turbine hub to have a core element for the sake of its attachment to a shaft, for example. In the simplest case, this core element can be designed as a sleeve and be connected nonrotatably to the shaft. A connection of this kind can be established by means of, for example, a set of drive teeth. The core element can have an internal set of teeth, which is brought into engagement with a set of external teeth on the shaft, such as a transmission input shaft.
It is also advantageous for the core element to be designed as a connection site for the turbine shell. In this case, it is advantageous for the core element to have, next to the area where it connects with the shaft (the first core element area), a radially outward-extending second area (the second core element area), which guides a radially inner area of the turbine shell, which can be fastened to this second area if necessary. The turbine shell can be attached to the core element in various ways. For example, it can be riveted, screwed, etc., to the core element. It is also conceivable, however, that the connection could be realized by means of a suitable welding process or the like.
It is advantageous for the core element to be designed to provide a radial and/or axial boundary of the sealing ring groove. Another boundary surface, as described further above, is provided by the turbine shell itself.
The core element can, for example, be designed to consist of two parts, namely, a first and a second core element part, where the first core element part has an attachment device (e.g., a set of teeth) for attachment of the turbine hub to the shaft. The second core element part is then connected in some suitable manner, such as by welds or an adhesive or the like, to the first core element part, so that it can extend outward in the radial direction.
It is then advantageous for the second core element part to be designed as a connection site for the turbine shell.
It is advantageous to provide the radially outer area of the (one-part) core element or the radially outer area of the second core element part (of a multi-part core element) with drive teeth to engage with a set of drive teeth on the torsional vibration damper and/or on the clutch piston.
It is preferable for the turbine shell to have an opening through which the set of drive teeth can pass.
As a result of the design described above, it is possible, first, to realize an extremely compact design variant, in which the individual components of the turbine hub and the turbine shell are guided in optimum fashion alongside each other and supported against each other. In addition, it is also possible for the turbine shell to take over certain functions of the turbine hub, such as the sealing ring groove function. The teeth provided in the outer area of the second core element part can pass through the opening in the turbine shell and project into the drive teeth of a torsional vibration damper. Of course, the teeth can also engage in a set of drive teeth connected directly to the clutch piston.
It is advantageous for the turbine hub to have an intermediate element for support against the housing. Regardless of whether the core element consists of a single part or multiple parts, this intermediate element represents an additional component of the turbine hub. For this reason, it is advantageous for the intermediate element to be connected to the core element of the turbine hub. For this purpose, it is advantageous for the intermediate element to be fixed permanently to the core element by a suitable welding process, adhesive bonding process, etc. Depending on the design of the individual elements of the turbine hub and of the turbine shell, however, it is also conceivable that the intermediate part could fixed in place by means of a pressing process or the like.
The intermediate element can be designed as a radial and/or axial boundary of the sealing ring groove. In this case, an axial boundary can again be provided by the turbine shell.
It is advantageous for the (one-part) core element and/or the second core element (of a multi-part core element) or the intermediate element to be designed as a connecting site for the torsional vibration damper.
It is preferable for the turbine hub to have at least one contact surface for at least one axial bearing and/or at least one roller bearing. The contact surfaces can in this case be provided on the core element and/or on the intermediate element of the turbine hub.
As a result of the contact surface(s) provided, the turbine hub or the individual components of the turbine hub can take over the job of providing radial and axial guidance for bearings such as axial bearings, roller bearings, etc. The turbine hub can in this way also perform the function of a plain bearing.
The turbine hub can also have a contact surface for the insertion of a rotary shaft seal.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.